| Blinding degenerative retinal diseases including retinitis pigmentosa, macular degeneration and glaucoma are characterized by loss of retinal neurons. At this time there is no way to replace retinal cell loss due to disease or injury since differentiated retinal cells are unable to regenerate. As a potential approach for treating retinal injury, neural progenitor cells have been proposed as a unique source of transplantable cells to replace lost cells in the damaged retina. Previous studies have transplanted a variety of neural stem cells to the eye in hopes of developing a therapy to replace retinal neurons lost to disease. Successful integration, survival and differentiation of the cell types have been variably successful. At the moment little is known about the fundamental biological differences between stem cell or progenitor cell types. Characterization of these differences will not only increase our general understanding of this broadly characterized group of cells, but also lead to development of criteria for sorting cells, evaluating their differentiation and predicting their suitability for transplantation.;In this dissertation we used protein expression profiling to characterize the molecular differences between two populations of in vitro expanded progenitor cells, retinal progenitor cells (RPCs) and brain progenitor cells (BPCs) isolated from mice of the same age and same genetic background. From this study we identified 4 stress-response proteins that were increased in expression in RPCs compared to BPCs. To see if these stress-response proteins were expressed during normal development, we used immunohistochemistry to characterize their expression in the developing retina. Finally, we tested the hypothesis that attenuation of oxidative stress would decrease the expression of stress-response proteins. We found that heat shock 60 (Hsp60), heat shock protein 70 (Hsp70), copper-zinc superoxide dismutase (Cu-Zn SOD) and catalase (CAT) are dynamically expressed in the developing retina. Further, we report that treatment of cultured progenitors with the antioxidant vitamin E (alpha-tocopherol) decreases expression of these proteins and alters their differentiation. These results are the first to characterize the expression of stress-response proteins during retinal development and demonstrate that reduction of oxidative load on cells can alter their differentiation profile. |
